Separation of solids from a liquid stream, using centrifugal separators is a well-established art. A stream of solids-laden liquid, often from a user device, usually water or an oil, are injected tangentially into a cylindrically-walled separation chamber. The stream whirls around the wall at a high speed while it also passes axially along the wall. Centrifugal forces move the solids closer to the wall.
The direction of axial flow is reversed at a spin plate that extends laterally in or adjacent to the separation chamber. At this point, the axial direction of the liquid stream reverses, and the stream, less solids, then flows upwardly closer to the axis of the chamber to an outlet port which may connect to the user device. Adjacent to the spin plate there is a gap through which the solids escape and flow into a collection chamber along with some of the liquid. The liquid which accompanies the solids is for convenience called a "carrier" liquid. In the existing art, the solids are collected from the collection chamber along with the carrier liquid.
A typical separator utilizing the above technique is shown in Steven D. Ford U.S. Pat. No. 5,368,735, issued Nov. 29, 1994 which is incorporated herein in its entirety for its showing of a suitable separator and full details of its operation.
The separators enjoy widespread use. In coarser applications they remove trash, cuttings, and trimmings from usable water in food processing plants, or in agricultural streams to remove particulates such as sand and trash, and in food preparation, such as in hot oil fryers for poultry and chips. Other examples are in mechanical workshops and machine shops where cuttings and chips must be separated from a cutting oil. Frequently the separator is connected in a closed circuit with a user device, receiving solid-laden liquid, removing solids, and returning the liquid for re-use. In other applications, the liquid is forwarded for another use, such as irrigation.
These separators collect the solids in the collection chamber, from which they are removed as a wet sludge or suspension. This is disposed of in various ways. When the liquid is benign and the solids are not objectionable, they are merely inconvenient trash and are disposed of as such. However, many times the carrier liquid may be toxic, such as cutting oils, and the collection must be disposed of as such, the carrier liquid adding to the costs or it may be inconvenient, for example a hot oil which is liquid while hot but which solidifies when cool. This becomes a very inconvenient thing to handle, especially when inexperienced help is utilized. An example found in fried food stands.
There are more demanding applications, where increased separation efficiency can greatly affect the economics of the entire operation. An example is in the cooking of masses in hot oil to create food products such as corn chips and potato chips. The cooking oil is costly, and must be kept clean of overcooked particulates that could change the flavor and appearance of the product. Any extension of time that a given change of oil can be used before it must be changed has a profound effect on the size of the manufacturing operation because of the cost of the oil and of the shut-down time needed to change the oil and clean the system. Deferring these events, enabling a longer use of the same oil, increases plant capacity and lowers the oil cost. Similar considerations apply in other fields, also.
In addition, there are safety considerations. When inflammable liquids are treated such as fuels, it is essential that no sparks be generated. A feature of this invention is that it is self-powered, and there are no moving parts or electrical connections. All power is supplied by the force and pressure of incoming the stream itself.
As a corollary, this invention, being self-powered, requires no energy beyond that which is provided by the stream itself (or the external pump which pressurizes it), and which is necessary for the separator to operate.
It will be noted that the only loss of liquid is that which is entrained in the collected solids, which is minimal. This improves the economy of the process, especially when large amounts of costly liquids are involved.
It is an object of this invention to provide in combination a centrifugal separator and a filter which, when linked according to this invention, will provide a nearly-dry collection of particulates (solids) with only minimal carrier liquid. The collected solids are accordingly much simpler to dispose of. The positive retention of the solids greatly reduces any tendency of solids to ingrate back into the liquid stream. The very clean effluent from the filter is returned to the stream, and improves the quality of the liquid that returns to the stream.